Rome, Italy

Visiting a city as beloved as Rome comes with particular hazards: the crowds, the cheesy souvenirs, the young men in full gladiator regalia waiting to pose for selfies with tourists.

And yet there are few places like it.

Take the Colosseum -- a nearly 2,000-year-old stadium in the middle of a modern city.

In the days of actual gladiators, 50,000 spectators would gather with the emperor for bloody contests to the death.

The Colosseum had the original retractable roof, a whizz-bang contraption called a velarium that used sail technology to rig canopies to shelter crowds from sun and rain.

And we've not even mentioned the Vatican, the catacombs or the Forum.

Istanbul, Turkey

Istanbul loves to depict itself as the city straddling two continents.

What's most remarkable is the way the city straddles great periods of history that pile up and fold over themselves more naturally than anywhere else in the world.

Construction by successive empires from Byzantium to Constantinople to modern Turkey have bequeathed Istanbul an instantly recognizable skyline that merges elements from all those eras.

In the historic core around the iconic Hagia Sophia, the Byzantine-era Hippodrome circus sits a short stroll away from the Ottoman Empire's Topkapi Palace, which houses artifacts including Moses's staff.

Surrounding it all is a thriving modern city with top-notch dining, galleries and architecture that make Istanbul one of the world's most important cultural centers.

Bagan, Myanmar

Less crowded than Angkor Wat and Machu Picchu, but just as magical.

Long hidden from international view by Myanmar's military government, the treasures of Bagan are returning to the spotlight as political reforms open up the country.

Here, over 2,000 Buddhist temples fill a plain along the Irrawaddy River, creating an ethereal landscape.

The crowds remain far smaller and more adventurous than the tour groups that fill Angkor Wat or Machu Picchu.

Myanmar is still finding itself after decades of civil war and international isolation, which makes this 11th-century temple city all the more magical.

The kingdom that reigned here was destroyed by earthquakes and Kublai Khan's invaders, but the quiet temples retain a spiritual air that's impossible to ignore.

Tikal, Guatemala

Hidden in the jungles of Guatemala, Tikal was a Mayan citadel that reflects more than 1,000 years of cultural achievements beginning from 600 BC.

Jaguars and pumas prowl the surrounding wilderness, but the palaces, temples and plazas within the site represent some of the earliest pinnacles of human achievement.

The stepped pyramids are icons of Mayan culture that rise above the canopy.

Equally impressive are the sporting courts, temples and palaces that ring the main plaza.

Most of the ancient causeways that link Tikal's 3,000 structures have been cleared of vegetation, so visitors can now wander among the buildings much as the ancients did.

Cairo, Egypt

For first-time visitors, it's a shock just how close the pyramids of Giza and the Great Sphinx are to Cairo's chaotic streets.

With 22 million people, Cairo is one of the world's biggest cities, built around one of humanity's earliest urban centers.

Tombs at Giza date back 4,500 years, and the Egyptian Museum of Antiquities boasts an incredible collection from the Nile's earliest inhabitants.

But the slightly less ancient parts of Cairo are also rich with cultural treasures.

The current city was founded more than 1,000 years ago and has one of the world's oldest universities, a rich legacy of Islamic art, and Coptic treasures that are often overlooked.

Persopolis, Iran

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Mohammad Reza Domiri Ganji's amazing photos of Iran are a great introduction to some of the country's rich cultural attractions. Among them is this literary institute in Shiraz, which has a reputation as a city of great poets and poems.

As Iran slowly reopens to Western tourism, Persepolis is regaining its allure for visitors.

The city was founded in 518 BC by Darius I, ruler of ancient Persia's Achaemenian Empire, and grew in grandeur until Alexander the Great sacked it two centuries later.

Its most remarkable feature is an immense terrace of 125,000 square feet, partially carved out of Mount Kuh-e Rahmat (the Mountain of Mercy).

Rulers built ever more regal palaces, temples and halls around the terrace, complete with an underground sewage system and cisterns for fresh water.

Despite a series of protective walls, rising to 30 feet high, Alexander laid waste to Persepolis, whose ruins were only rediscovered in 1618.

Today, however, the city is one of the best examples of ancient architecture, especially for the slender columns that remain.

Kyoto, Japan

Kyoto cool: Japan's former capital preserves old traditions.

If Tokyo represents the part of Japan obsessed with technology and the future, Kyoto is the part that rakes sand in Zen gardens and performs graceful tea ceremonies.

That's not entirely fair -- Nintendo is based in Kyoto, just one part of the city's thriving tech scene.

Perhaps closer to the truth is that as imperial Japan's capital for more than 1,000 years, Kyoto has found a way to respectfully preserve its old traditions while eagerly embracing the new as well.

More than 1,000 Buddhist temples and Shinto shrines temper the frenetic pace of modern life.

Since the city was largely spared bombing during World War II, most are still in use.

Beijing, China

China has invested heavily in eye-popping modern architecture for its capital over the last two decades, but with a past that stretches more than 3,000 years, the city has a deep history providing a rich legacy of art, architecture and education.

Just visiting the city's six UNESCO World Heritage sites, including the Forbidden City and the Temple of Heaven, could take a week.

That would barely allow even a casual glance at the treasures inside the city's 144 museums and galleries, much less the alleyways of the hutongs, old neighborhoods reinvented and sometimes rebuilt as a trendy center of the Beijing's modern life.

Great Zimbabwe, Zimbabwe

From the 11th century, this kingdom in southeastern Zimbabwe grew into a trading empire that stretched through the African interior and across the Indian Ocean.

A royal complex grew on a hilltop, with drystone architecture creating a terraced palace with fruit trees, hidden chambers and stunning views over the king's dominion.

Below, the towering walls of the Great Enclosure surround a conical tower that's become a national symbol.

Overpopulation and deforestation caused the kingdom's collapse around 1450 -- historically bad timing as Europeans soon began arriving to find a weakened polity that was easier to subdue.

Great Zimbabwe remains a monumental reminder of Africa's achievements before colonialism.

Many brim with tourist tchotchkes, but with enough art galleries and good eating mixed among them even the most jaded traveler will be satisfied.

Much of the city's social life centers around the monuments, turning the stunning ruins of classical Greece into casual backdrops of Athenians' every day lives.

Petra, Jordan

This region between the Dead Sea and the Red Sea has been inhabited since the earliest days of humanity, but around 300 BC the rulers of the Nabatean Kingdom laid their claim to cultural greatness by carving magnificent buildings into red sandstone cliffs.

Gorges and canyons surround the ancient city, creating a maze of passages that helped keep it secret from Europeans for centuries.

Adding to the mystique: no cars are allowed in the ancient city.

Visitors who don't want to walk have to hire a camel, donkey or carriage to get around.

Ellora, India

Like Petra, Ellora was carved out of the mountains in the area of Maharashtra.

But this Indian monastic complex remains relatively unknown.

The temples include Hindu, Buddhist and Jaina holy sites that were built over 400 years, beginning in the 6th century.

The most impressive has the uninspiring official name of Cave 16, known informally as Kailasa, and the entire temple was carved out of a massive rock face.

The double-story entrance leads to a courtyard surrounded by a three-story arcade lined with columns. The building is twice as large as the Parthenon.

Inside, images of Hindu deities were sculpted from the stone, with two life-size statues of elephants in the courtyard.

Xi'an, China

In addition to the famed Terracotta Warriors, Xian's well-preserved city wall is worth a visit.

In the Silk Road's heyday, Xi'an was where the journey west began.

For more than a millennium, Xi'an was the capital of ancient Chinese dynasties.

Now it's most famous as the home of the Terracotta Warriors -- thousands of clay soldiers that fill the mausoleum of Emperor Qin Shi Huang. Each is standing, ready for battle, but they had been buried underground for 2,000 years.

Workers digging a well stumbled upon one of the soldiers in 1974, leading to one of the great archeological finds of all time.

Excavation is still underway, and more recent work has discovered statues of dancers and acrobats, giving a new sense of the grandeur of Qin's ambitions.